Common endoscopic procedures like colonoscopy may be more likely than previously thought to cause complications, according to a study in the Archives of Internal Medicine.

Researchers at Beth Israel Deaconess Medical Center in Boston designed a system to examine electronic medical records detailing more than 18,000 endoscopic procedures. The system recorded all emergency department admissions to the hospital with 14 days of the procedures.

There were 419 admissions resulting in 266 hospitalizations, according to the study. Thirty-two percent of the ER admissions and 29 percent of the hospitalizations were deemed related to the endoscopies, versus only 31 complications reported by doctors at the hospital.

The researchers "observed a 1 percent incidence of related hospital visits within 14 days of outpatient endoscopy, two- to three-fold higher than recent estimates," according to the study. "Most events were not captured by standard reporting, and strategies for automating adverse event reporting should be developed."

The extra ER visits and hospitalizations added $48 per examination, the researchers found, taking the mean costs to about $1,400 per ER visit and more than $10,000 per hospitalization.

"The cost of unexpected hospital visits post-endoscopy may be significant and should be taken into account in screening or surveillance programs," the researchers wrote.